Viana do Castelo weather in May

In May, Viana do Castelo sees average daytime highs of 19°C and overnight lows near 12°C, with 133 mm of rain across 11.8 wet days and about 14.3 hours of daylight. It is the 6th-warmest and 8th-wettest month of the year here.

Highs climb over the month, from about 17°C in the first days to 20°C by the end. The sky is clear or mostly clear about 36% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 48 min at the start of May to 14 h 48 min by month's end. Set against the rest of the year, May is Viana do Castelo's 5th-clearest and 7th-windiest month. For the whole year in context, see Viana do Castelo's year-round climate.

Daytime high
19°
6th warmest
Overnight low
12°
7th coldest
Rainfall
133 mm
11.8 wet days
Daylight
14 h 18 min
5:21 AM – 7:42 PM
Cloud cover
52%
5th clearest
Wind
13 km/h
7th windiest
Solar energy
6.5 kWh/m²
Travel score
5.9
out of 10

Viana do Castelo is city seat of Viana do Castelo municipality in northern Portugal and seat of the municipality and district of the same name.

Air quality
Excellent
PM10 9.1 µg/m³ · 2013

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 17°C in the first days to 20°C by the end.

A typical May day in Viana do Castelo reaches about 19°C in the afternoon and slips back to 12°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 15°C and 23°C. Set against its neighbours, May runs about 2°C warmer than April and about 3°C cooler than June.

10°15°20°25°30°151015202531
Avg high (°C)Avg low (°C)
11711
21711
31711
41811
51811
61811
71811
81811
91811
101811
111811
121811
131812
141812
151912
161912
171912
181912
191912
201912
211912
221912
231912
241913
252013
262013
272013
282013
292013
302013
312013

Viana do Castelo weather by month

How May compares with the rest of the year at a glance. May is the 6th-warmest and 8th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan13° / 21813.69.33.3
Feb14° / 14210.410.33.9
Mar15° / 16511.311.74.7
Apr17° / 10°1541313.15.0
May19° / 12°13311.814.35.9
Jun21° / 14°566.9157.2
Jul23° / 16°324.414.78.4
Aug24° / 16°45513.78.3
Sep22° / 15°897.412.37.3
Oct19° / 13°23213.210.95.7
Nov15° / 10°23214.29.64.3
Dec13° / 22714.193.5

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 36% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 19% of May, with mostly cloudy or overcast conditions the remaining 46%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
15050
25050
35149
45149
55149
65149
75149
85149
95149
105149
115149
125248
135248
145248
155248
165347
175347
185446
195545
205644
215644
225743
235842
245842
255941
265941
275941
285941
295941
305941
316040

Chance of precipitation in May

Any precipitation

Viana do Castelo gets around 133 mm of rain over 11.8 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 38% and peaks near 42% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%40%50%151015202531
Rain chance (%)
142
241
341
441
541
641
741
841
940
1040
1140
1240
1340
1439
1539
1639
1739
1838
1938
2037
2137
2236
2336
2436
2535
2635
2734
2834
2933
3032
3132

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

Most of May feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, May lands in the dry band about 72% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)
187130
286140
386140
485150
585150
684160
784160
882171
981181
1080191
1180191
1279201
1378211
1477221
1575241
1673252
1772262
1871272
1969283
2068293
2166304
2265314
2363325
2461336
2560346
2658357
2757367
2855378
2954388
3053398
3152399

Wind in May

Winds average 13 km/h in May.

Across May, daily wind ranges from about 12 km/h on the calmest days to 13 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202531
Wind speed (km/h)Feels
113light breeze
213light breeze
313light breeze
413light breeze
513light breeze
613light breeze
713light breeze
813light breeze
913light breeze
1013light breeze
1113light breeze
1213light breeze
1313light breeze
1413light breeze
1513light breeze
1613light breeze
1713light breeze
1813light breeze
1913light breeze
2012light breeze
2112light breeze
2212light breeze
2312light breeze
2412light breeze
2512light breeze
2612light breeze
2712light breeze
2812light breeze
2912light breeze
3012light breeze
3112light breeze

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 48 min at the start of May to 14 h 48 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 60 minutes over May. Sunrise moves from 5:39 AM to 5:10 AM, and sunset from 7:26 PM to 7:56 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.85:397:26
213.85:387:27
313.95:377:28
413.95:357:29
513.95:347:30
614.05:337:31
714.05:317:32
814.15:307:33
914.15:297:35
1014.15:287:36
1114.25:277:37
1214.25:267:38
1314.25:247:39
1414.35:237:40
1514.35:227:41
1614.35:217:42
1714.45:207:43
1814.45:197:44
1914.45:187:45
2014.55:187:46
2114.55:177:47
2214.55:167:48
2314.65:157:49
2414.65:147:50
2514.65:137:51
2614.65:137:52
2714.75:127:52
2814.75:117:53
2914.75:117:54
3014.75:107:55
3114.85:107:56

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 6.5 kWh/m².

For context, solar energy here swings from a low near 1.59 kWh/m² to a high of 7.29 kWh/m² in July across the year — May's 6.5 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
16.0Intense
26.0Intense
36.1Intense
46.1Intense
56.1Intense
66.2Intense
76.2Intense
86.2Intense
96.3Intense
106.3Intense
116.3Intense
126.3Intense
136.4Intense
146.4Intense
156.5Intense
166.5Intense
176.5Intense
186.6Intense
196.6Intense
206.6Intense
216.7Intense
226.7Intense
236.7Intense
246.7Intense
256.8Intense
266.8Intense
276.8Intense
286.8Intense
296.9Intense
306.9Intense
316.9Intense
Planning a trip in May

Hazard calendar for Viana do Castelo

In seasonPeak

In May, Viana do Castelo sits inside its rainy season season. The full year is below, with each hazard's peak months called out.

Viana do Castelo's rainy season runs October–May, when most of the year's rain falls.

Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is May a good time to visit Viana do Castelo?

Our two travel scores rate May for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

5.9
Sightseeing
5th-best month of the year
2.4
Beach & pool
6th-best month of the year

May is a reasonable time to visit Viana do Castelo for sightseeing.

What to pack for Viana do Castelo in May

From May's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In May, Viana do Castelo sees daytime highs around 19°C and nights near 12°C. Pack sun protection. Worth having: rain gear. About 12 days see rain.

sun protectionrain gear

Sea temperature near Viana do Castelo in May

The nearest coast averages about 15°C in May — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in August at about 17°C and coldest in February near 13°C.

The water stays below 20°C all year — cool enough that most swimmers want a wetsuit.

12°14°16°18°JanFebMarAprMayJunJulAugSepOctNovDecbracingcool
Sea temperature (°C)Comfort
Jan14Bracing
Feb13Bracing
Mar14Bracing
Apr14Bracing
May15Cool
Jun17Cool
Jul17Cool
Aug17Cool
Sep17Cool
Oct17Cool
Nov16Cool
Dec15Bracing

UV index in Viana do Castelo in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Viana do Castelo peaks around June 23 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 20 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJun 23UV 9Dec 20UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May7High
Jun9Very high
Jul9Very high
Aug8Very high
Sep6High
Oct4Moderate
Nov2Moderate
Dec2Low
Location & terrain

Where is Viana do Castelo?

Viana do Castelo sits at 41.7°N, 8.8°W, 12 m above sea level, in Portugal. The nearest listed city is Esposende, 18 km away.

Topography around Viana do Castelo

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Viana do Castelo.

Within 3 km, the terrain around Viana do Castelo has significant variations in elevation — a maximum elevation change of 300 m around an average of 29 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 793 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,517 m.

The land around Viana do Castelo is covered by water (37%), trees (23%) and artificial surfaces (22%) within 3 km, water (47%) and trees (29%) within 16 km, and trees (38%), water (32%) and grassland (22%) within 80 km.

3 km
300 m
16 km
793 m
80 km
1,517 m
treesshrubsgrasslandcroplandartificial surfacesbare terrainwaterwetland
May weather nearby: Esposende 18 km · Ponte de Lima 22 km · Barcelos 25 km · Pedroso 32 km · Póvoa de Varzim 35 km · Braga 38 km · Arcos de Valdevez 38 km · Vila do Conde 38 km

Portugal travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type C / E / F
230 V · 50 Hz
Prices
≈ 60% of US
price level, 2025
GDP per capita
$32,082
2025
Happiness
6.0 / 10
World Happiness, 2025
Safe drinking water
95%
of population, 2024
Homicide rate
0.7
per 100k, 2022
Road deaths
8.2
per 100k/yr, 2019
Income group
High
World Bank
English
Very high
EF EPI 612
Religion
Catholic 68%not applicable 13%no religion 12%no response 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Viana do Castelo (41.6932°, -8.8329°, elevation 12 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).